1. Field of the Invention
The present invention relates to keyboard keys with marked elastic domes and the fabrication method thereof, and in particular to elastic domes with geometric marks for the keys of a notebook computer and the fabrication method thereof.
2. Description of the Related Art
FIG. 1A is an exploded view of a conventional keyboard. FIG. 1B is a cross section of a key of a notebook computer. In order to simplify the drawing, FIG. 1A only shows one key of a conventional keyboard. In FIG. 1A, the key of a keyboard for a notebook computer includes a key cap 11, a cap support 12, an elastic sheet 13, a circuit membrane assembly 14 and a base sheet 15.
The base sheet 15 is a metal sheet on which two seats 151 and a hook 152 are formed by punching and contacting.
The circuit membrane assembly 14 is disposed on the base sheet 15. It comprises the circuit of the keyboard and a plurality of holes 141 with respect to the seats 151 and the hook 152 of the base sheet 15.
The elastic sheet 13 has a sheet-like body, an elastic dome 131, a connecting portion 133 and holes 132. The connecting portions 133 connect the elastic dome 131 and the sheet-like body. Further, the elastic dome 131 has a plunger (not shown) inside to contact the circuit membrane assembly 14 and conduct the circuit thereto.
The cap support 12 has a first linking bracket 121 and a second linking bracket 122. The shaft portions 1221 of the second linking bracket 122 are inserted into the holes 1211 of the first linking bracket 121, so that the first linking bracket 121 and the second linking bracket 122 are hinged together. This structure is known as a scissors-type support mechanism. Furthermore, the first linking bracket 121 has shaft rods 1212. The second linking bracket 122 has shaft rods 1222 on its corners.
FIG. 1C is a schematic back view of a key cap of the key in FIG. 1A. In FIG. 1C, the key cap 11 has hooks 111 and holding portions 112, 113 on its bottom surface.
In FIGS. 1A˜1C, while assembling the conventional keyboard, the circuit membrane assembly 14 and the elastic sheet 13 are put on the base sheet 15. The seats 151 and the hook 152 of the base sheet 15 protrude through the holes 141 of the circuit membrane assembly 14 and the holes 132 of the elastic sheet 13. The key cap 11 is mounted on the base sheet 15 via the cap support 12. The shaft rods 1212 are inserted into the seats 151 SO that the first linking bracket 121 is rotatable with respect to the base sheet 15. The narrow portion 1221 of the second linking bracket 122 is hooked by the hook 152 of the base sheet 15 so that the second linking bracket 122 is also rotatable with respect to the base sheet 15. The hooks 111 hold the shaft rods 1212 of the first linking bracket 121, and the holding portions 112, 113, hold the shaft rods 1222 of the second linking bracket 122. Furthermore, the L-shaped hooks 111 contact the first linking bracket 121 in FIG. 1C.
In operation, the user pushes down the key cap 11 and compresses the elastic dome 131. Then, the plunger of the elastic dome 131 contacts the circuit membrane assembly 14 so that a completed circuit is induced to send out a corresponding signal.
The elastic domes of conventional keyboards are made by molding. An elastic membrane with a plurality of elastic domes is first formed. The elastic domes are separated from the elastic membrane, and then the elastic domes are bonded on the elastic sheet 13 arbitrarily. During the process, however, when elastic domes are broken, it is unknown which mold cavities have defects, or whether the mold or jigs are improperly designed. Thus, there must be an additional sifting process during assembly. The broken elastic domes must be sifted out before the adhesion process to avoid producing keyboards with bad keys, and thus the sifting process causes the running cost of manufacturing keyboards to increase.